The world’s population quadrupled over the course of the 20th century and now stands at 6.7 billion. Since 2000 it has increased by 700 million, which is equivalent to the entire population rise in the 19th century. In the 18th century, it rose by a mere 200 million. As their numbers have grown, human beings have gravitated increasingly toward cities, which have also grown as a result. Since 2007, more than one in two of us live in a town or city.
There are more people in some of the bigger cities—such as Tokyo, with its population of 35 million—than in some countries as a whole. In developing countries, urban growth can occur at a rate that is simply mind-boggling. Dhaka, the capital of Bangladesh, had a population of 300,000 in 1950, whereas today the figure stands at more than 15 million: a fiftyfold increase in fifty years. Boom towns such as Dhaka face immense problems in terms of infrastructure including electricity, drinking water, and waste disposal.
Nevertheless, this demographic explosion and the urbanization linked to it seem also to hold part of the solution. Birth rates have been shown to be decreasing over a great many parts of the globe, particularly in urban areas. The current average stands at 2.6, with significant regional disparities. In many Western countries, it has even fallen below 2.1, the threshold for population increase. The world population is shrinking and ageing. Whereas earlier projections for the coming decades envisaged a global population of 12 billion, the estimate has fallen and it is now thought that the population should stabilize at around 9 billion by 2050.
This seems to be due to the fact that city-dwellers generally have better access to education. For many women, in particular, this signifies access to information and to methods of contraception. It also means that these women are often able to work in addition to having a family. Having children becomes a choice, to be balanced against a career, for example. Urban life, moreover, changes people’s behavior and living requirements: couples have fewer children than those living in the country since they no longer need help in the fields. This reduction in the birth rate responds to one of the major challenges of the century: that of population control as a means of successfully feeding the world and saving the planet.